Icebreakers are special-purpose ships designed to operate in different ice-covered waters, either independently or duringassistance of weaker ships. In the Baltic Sea, as well as elsewhere, they are essential for maintaining continuous sea transportservices during wintertime. Icebreaker operations are complex, and every situation in which a vessel requires assistanceis unique, due to, e.g. changing ice and weather conditions, geographical location or language proficiency of the crew onboard the icebreaker or assisted vessel. The icebreaker crew has considerable freedom to adapt to each situation, yet, forsafe operations, there are constraints to which the crew has to conform. The study presented in this paper aims at identifyingthe constraints on nautical officers on board icebreakers during operations, as well as special situations that increasecognitive load. A work domain analysis based on a group interview with nautical icebreaker officers shows the multitudeof tasks performed on board icebreakers. Furthermore, it identifies constraints specific to icebreaker operations such as iceassessment and direct icebreaking, but also generic constraints such as language and communication skills. At times, safetyand efficiency come into conflict, resulting in a trade-off between the two. When that happens, safety gets priority, and theoperation stops until the situation has been evaluated. In addition, several situations that increase cognitive load are identified,with the common denominator that they add elements of uncertainty, e.g. severe weather and technical malfunctions.Finally, further research within the area of icebreaker operations is recommended, with a continued focus on the systemconstraints, and their potential for system improvement.

The study presented in this paper aims at investigating what safety measures that can be taken to improve the operational safety during icebreaker operations in the Baltic Sea. During icebreaker operations, the icebreaker and the assisted vessel operate in close proximity to each other, a distance which can be even smaller if weather and ice conditions are severe. This poses a severe threat to the operation, since the extremely short distance between the vessels leaves no room for error. The results, which are based on data collected through individual interviews and questionnaires, indicate several possible improvements. Firstly, on a regulatory level, the introduction of an ice navigation certificate for deck officers would set a minimal level of formal competency. Secondly, on a knowledge level, more ice navigation training and better language skills work in favour for the safety. Thirdly, on a technical level, having an electronic chart with target tracking capability increases the efficiency and safety of the passage through ice. In addition to these results, this study shows a need to further research the communication and language situation during icebreaker operations.

Icebreaker operations, when an icebreaker assists other vessels through ice-packed fairways, are hazardous due to harsh environmental conditions and complexity of procedures. The severity of operations is further aggravated by the necessity for maintaining a small distance between the vessels, which consequently increases the risk of collision. Even though miscommunication is widely identified as a contributing factor to shipping accidents, previous research within winter navigation has focused largely on technical aspects of icebreaker operations to increase the operational safety. This study aimed to investigate to what extent closed-loop communication is used during icebreaker operations, and whether this practice deviates from stipulated communication protocols. A quantitative analysis was performed, coding 40 days of verbal radio communication. Subsequently, the data was compared to the stipulated communication protocol outlined in the Standard Marine Communication Phrases. The results show that closed-loop communication is not utilized to its full extent. Some message types are completely repeated at a higher rate, mainly instruction and question, while other message types, such as information and intention often receive a yes-no answer. A full closed-loop, i.e. a completely repeated message followed by a confirmation, was only observed in 16.4% of the messages initiated by an icebreaker and 14.0% for the assisted vessels. Thus, this study clearly shows that there is a gap between actual language use and stipulated communication protocol. Finally, since misunderstandings during icebreaker operations can have serious consequences, more research is needed into the underlying reasons for miscommunication in situations with little room for error.

Communication is an essential part of most joint activities, and effective means to identify and rectify misunderstandings are necessary to reach mutual understandings. In the maritime domain, faulty communication is often a contributing cause to ship accidents, potentially putting human lives, vessels, and the environment at risk. This study explores the use of other-initiated repair in maritime ship-to-ship communication. The purpose is to classify and analyse other-initiated repair and describe the specific practices used to initiate repair and rectify mistakes. Based on an analysis of authentic communication between vessels involved in icebreaker operations, findings indicate that other-initiated repair occurs less frequently in this corpus compared to other corpora of naturally occurring conversations. A possible reason is that radio communication, which is highly structured, has other means to identify communicative errors. More than half of the repair initiations use open requests to identify a trouble turn, and the most common repair solution is a full or partial repeat. Furthermore, maritime radio communication has an inherent slowness due to technical limitations that do not permit simultaneous talk. It is argued this refrains speakers from using long or complex messages, as the listener has no way to indicate trouble until next turn.